For the nut cake, beat the egg yolks with sugar until very foamy, whisk the egg whites with salt until stiff and then add the not too finely ground hazelnuts and flour mixed with baking powder.
Fold everything in carefully with a whisk. Pour the batter into a springform pan (26 cm) greased on the bottom, bake in a preheated oven at 200 °C for about 30-35 minutes and leave in the turned-off oven for another 5-10 minutes.
Carefully remove the cake from the oven and let it cool in the pan, as it collapses easily. Whip the cream with cream stiffener and sugar.
Cut the cake twice and fill it with the cream. Decorate the cake with top dabs and hazelnut kernels.